What year did the military start implementing scopes with Horus H58/H59 reticle and which scopes were they first offered in besides the Horus brand scopes? Which branch got them first?
The US Army fielded M110 with the Leupold M3LR as specified in MIL-PRF-32316 (AR) w/AMENDMENT 1, 5 October 2009 (superseding 7 October 2008).
People confuse the KAC M110 (Army contract) with the USSOCOM SR-25 (1993-2000) and Mark 11 (fielded in 2000).
M110 users might have US Army tapes on their uniform jackets but there were two buyers -- the Navy (with SOCOM-provided money for US Commandos) and Mother Army (for Active, Guard, and Reserve Soldiers).
Two different and distinct customers and contracts, both with different contract acceptance specs.
You get two M110s per SFODA because the Army is bound (by law) to provide Army-common equipment to a slotted sniper. An SF Soldier or Ranger might also have a Mark 11 as well, with an M110A3 (6.5 Creedmoor) upper.
Guys like Rangers or SF never ended up with leupolds that Horus reticle in them on the 110/SR25? I know they started training with Accuracy 1st at some point.
I recall an unofficial horus fam fire once ~2011. I would think cool guys could put mk4 ERT h58s on the m110 anytime they wanted after 2010 but I have no knowledge it was ever purchased/issued like that. Conventional roleplayers (my exp) may have put other issued optics on the m110 [rare, probably dicking around] but the m110s I'm familiar with came in a big tan box w the x40mm TMR.
Edit: added [rare dicking around] to not give the wrong idea
Infantry snipers are not USASOC (Ranger, SF, and SMU) snipers. Vanilla Army frowns on innovation and initiative so I doubt they used any variations.
SOTIC (now SF Sniper School) was influenced by SMU snipers who had contracted Todd Hodnett for training around 2008-2010. Todd introduced them to Horus scopes and reticles and non-dialing. A few loaners and trial buys led to more work and development until Leupold put the H58 in the XM2010 optic.